Pseudocyst of the testis of a prepubertal horse.

This study describes a unique case of a testicular pseudocyst, a fluid-filled cavity without pus or epithelial lining, in a prepubertal horse. The condition was identified and treated at the Western College of Veterinary Medicine, with this being the first published report of such a condition in a horse.

Case Presentation

• The subject of the case was a six-month-old Belgian colt, presenting with acute swelling of the scrotum and prepuce. The horse had been seen jumping over fences, with the owner noting frequent jumping from the colt in the past.
• Prior to being examined in the college, the horse’s condition had been treated with Furosemide by another veterinarian due to concerns of an inguinal hernia, testicular rupture, hematoma, or an abscess.

Preliminary Examination

• On examination, the colt had normal temperature, pulse and respiration although a large mass was felt in the right side of the scrotum.
• The mass was very large, oval and firm, felt slightly painful and wasn’t movable within the scrotum. Its measurements, though considered inaccurate due to the difficulty of handling the colt, were significantly larger than those obtained after surgery.
• The left testicle, which appeared small and was located high in the scrotal sac, appeared normal over ultrasound imaging.

Findings and Diagnosis

• Ultrasound imaging of the right scrotum showed hypoechoic circular areas, spots with less echo on ultrasound, within a large hyperechoic, a spot producing stronger echo, oval mass. This led to a tentative diagnosis of an enlarged right testicle.
• Differential diagnoses considered were orchitis (inflammation of the testicle), testicular torsion with vascular compromise, hematoma (an abnormal collection of blood outside the blood vessels), and neoplasia (new, uncontrolled growth of cells).
• In addition to the diagnostic imaging, a complete blood count (CBC) and plasma protein measurement showed a mature neutrophilia – an abnormally high number of neutrophils, a type of white blood cell, which could indicate infection, with a mild shift to the left, signifying an increase in less mature cells.